Electrocatalysis最新文献

Hydrogen peroxide (H₂O₂) is a common and important oxidizing agent, which is widely used in environmental protection fields. In this study, the COF framework catalysts with nickel-cobalt bimetallic sites, Co@phthalocyanine (PcNi) - tetrahydroxybenzene (THB), were synthesized through the hydrothermal method. These catalysts were applied as the particulate electrodes in the electrocatalytic hydrogen peroxide (H₂O₂) generation system. Scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterized the Co@PcNi-THB particle electrodes. Scanning electron microscope (SEM) images showed the Co@PcNi-THB particle electrodes featured the porous structure. The electrochemical active area of Co@PcNi-THB increased to (3.97 µF/cm²), which was 2.39 times higher than that of PcNi-THB catalyst (1.66 µF/cm²). The maximum H₂O₂ yield of 3340 µmol/g was obtained with the addition of Co@PcNi-THB catalyst content of 10 mg, current density of 15 mA/cm², pH 11.03, continuous stirring for 1 h at 200 r/min using a magnetic stirrer, and 0.1 M Na₂SO₄ electrolyte, with an energy consumption (EEC) of 3.201 kWh/kg. The acidic atmosphere, Cl⁻ and NO₃⁻ ions have the inhibitory effect on the H₂O₂ yields. After five cycles of Co@PcNi-THB, the H₂O₂ production decreased to 3153 µmol/g, and the retention ratio of Co in Co@PcNi-THB reduced to 94%. Under the same reaction conditions, the Faraday efficiency (FE) obtained using the gas diffusion electrode (GDE) for the Co@PcNi-THB method was 76.4%, and the hydrogen peroxide yield was 3885 µmol/g. The synergistic Co-Ni effect generated by the introduction of the metal Co enhanced the two-electron Oxygen Reduction Reaction (2e⁻ORR) process. This study provides new insights for designing particle electrodes with bimetallic atomic synergistic effects.

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Ketjenblack supported Ni electrocatalysts (Ni/C) with nickel content from 20% to 70% were synthesized by the impregnation method using freeze-drying. Cyclic voltammetry, transmission and scanning electron microscopy were applied for characterization of the Ni electrocatalysts. The prepared samples were tested in the glycerol electrooxidation reaction in alkaline media along with Ni black and Ni rod. It turned out that the onset potentials of glycerol electrooxidation were notably lower for the supported Ni electrocatalysts than for Ni black and Ni rod. Among the supported Ni electrocatalysts, the sample with nickel content of 60% was found to be the most active. The onset potential for glycerol electrooxidation on 60% Ni/C is about 200 mV lower than the values reported in the literature.

Developing efficient catalysts for the electrochemical nitrogen reduction reaction (NRR) under mild conditions remains a key challenge toward sustainable ammonia production. In this work, the microwave-assisted hydrothermal synthesis of Ce-doped Fe₂(MoO₄)₃ is reported as an effective and robust electrocatalyst for N₂ reduction. Structural (X-Ray Diffraction and Raman) and compositional characterization (Energy Dispersive Spectroscopy) confirmed the successful incorporation of nominally 2% cerium into the structure with a homogeneous distribution across the bulk catalyst without significantly altering the crystal structure. Electrochemical tests conducted in phosphate buffer (PBS, 0.1 mol L⁻¹, pH 7.0) saturated with N₂ demonstrated that the 2% Ce–Fe–Mo sample achieved the highest ammonia production: 12.8 µmol/L and 42% Faradaic efficiency for 2 h electrolysis at + 0.022 V vs. RHE. Normalization by mass and electrolysis time revealed that this low overpotential electrolysis effectively suppressing hydrogen evolution, provides a twofold increase in NH₃ production compared to similar processes reported at more negative overpotentials. Chronoamperometry (7 h) followed by post-electrolysis Raman spectroscopy confirmed electrochemical and structural stability under these conditions. The improved performance is attributed to the synergistic interaction between Mo and Ce facilitating N₂ adsorption and conversion. Ce-doped Fe–Mo oxides are promising candidates for ambient N₂-to-NH₃ conversion via electrochemical pathways, combining high efficiency, stability, affordability and significant cost-benefit advantage compared to noble-metal-based systems.

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A highly efficient and reliable electroanalytical biosensor for the estimation of melatonin (ME) employing pretreated graphene nanosheet uniformly-wrapped Ru nanoparticles (PTGNS/RuNPs) nanocomposite rational designed oxidized polydiaminonaphthalene/taurine (OPDAN/TA) has been performed. The OPDAN/TA/PTGNS/RuNPs nanocomposite biosensor has been characterized with numerous techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR). The PTGNS/RuNPs structure has been uniformly dispersed and influentially utilized into the OPDAN/TA that improves nanocomposite performance toward the estimation of ME. The nanocomposite biosensor not only inherits the electrochemical active surface area of PTGNS/RuNPs, while appears an excellent conductivity and electrocatalytic performance of the oxidized conducting copolymer PDAN/TA. A great and excellent sensitive achievement is conducted with the biosensor that was electropolymerized in deep eutectic solvents (DES) to improve catalytic effectives to ME with high influential charges transport voltammograms, while eliminated any biological interfering species. Furthermore, the nanocomposite biosensor was then utilized in the estimation of ME with the wide linear range from 1.0–160 μM, the limit of detection (LOD) and limit of quantitation (LOQ) of 0.015 ± 0.002 µM and 0.050 ± 0.002 µM with a sensitivity value of 4.2 μA μM^–1. The reproducibility and repeatability of the biosensor were also examined with the relative standard deviation (RSD) of 3.23 and 3.62, respectively. The high selectivity and stability of the OPDAN/TA/PTGNS/RuNPs biosensor to ME estimation may be because of the functionality and surface nature of the OPDAN/TA that was completely dispersed on the PTGNS/RuNPs nanocomposite. Finally, the proposed nanocomposite biosensor was operated successfully and applied to the analytical examination of ME in biological fluids samples.

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An innovative electrochemical dopamine sensor was fabricated by integrating zinc oxide nanoparticles and poly(cyanocobalamin) onto a screen-printed carbon electrode. Utilizing almond gum as a reducing agent, a sustainable synthesis method yielded crystalline ZnO nanoparticles under ambient conditions. The nanocomposite-modified electrode was thoroughly characterized using state-of-the-art spectroscopic and microscopic techniques. Voltammetric analysis demonstrated a linear correlation between dopamine concentrations (100–600 µM) and electrochemical response, exhibiting a sensitivity of 1.3725 µAµM⁻¹cm⁻² and a detection limit of 1.6047 µM. The sensor’s performance was confirmed through successful real-sample analysis, showcasing its potential for practical utility. Comparative evaluation with our existing electrodes underscored the benefits of this novel approach.

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The rising demand for energy and environmental concerns necessitate sustainable CO₂ utilization. The electrochemical CO₂ reduction reaction (CO₂RR) has emerged as a promising approach for converting CO₂ into fuels and chemicals. The metal-free carbon materials with nitrogen doping have shown great potential in CO₂RR to produce CO, and pyridinic-N is widely believed to be the responsible active sites. The directed preparation of pyridinic-N dominated carbon and the finely regulation of nitrogen content should be vital for regulating the CO₂RR performance and exploring the catalytic mechanism, which are still challenging. This study developed nitrogen-doped carbon nanotubes (N-CNT) with pyridinic-N domination through pyrolysis of oxidized CNT (OCNT) under ammonia. The nitrogen contents of N-CNT were regulated by adjusting the time for acid-oxidizing treatment, ranging from 5 h to 24 h. N-CNT with oxidizing time of 24 h (N-CNT-24 h) demonstrates the highest nitrogen content and the greatest CO₂RR activity among the samples, with a maximum Faradaic efficiency (FE) of 95% for CO production, maintaining FE of 90% over 11 h of electrolysis. This research provides insights into selectively introducing Pyridinic-N into CNT and examines the effects of nitrogen doping on catalytic performance, contributing to the design of efficient metal-free carbon-based electrochemical catalysts for CO₂ reduction.

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Brackish water is an attractive feedstock for large-scale hydrogen production, but the high concentration of Cl⁻ ions causes severe electrode corrosion and efficiency loss. Here, Fe-doped molybdenum sulfide was grown on nickel foam by a hydrothermal route to address this issue ((MoFeNi)₃S₂). The introduction of Fe strengthens the bonding within the sulfide framework, which helps to stabilize the structure and reduce the damage caused by halogen ions. In parallel, Fe also tunes the electronic state of the active sites, leading to higher catalytic activity. In 1.0 mol L^− 1 KOH + 0.5 mol L^− 1 NaCl electrolyte, the catalyst delivers bifunctional activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), achieving 10 mA cm^− 2 at an overpotential of 225 mV (OER)/53 mV (HER), and retaining OER stability for 384 h at 1000 mA cm^− 2. A full alkaline electrolyzer with (MoFeNi)₃S₂ electrodes operates continuously for over 264 h, highlighting its promise for overall water splitting in saline environments. This research provides a promising theoretical approach for the development of corrosion-resistant catalysts that can efficiently and stably produce hydrogen through alkaline saline water electrolysis.

The study aimed to enhance the performance of microbial fuel cells (MFCs) by employing carbon cloth anodes modified with ferric oxide (Fe₂O₃) and hydrogen peroxide (H₂O₂) for the treatment of distillery wastewater. Two double-chambered MFCs were developed: MFC-1 utilized standard carbon cloth, whereas MFC-2 featured carbon cloth anodes treated with Fe₂O₃/H₂O₂. Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of oxygen-rich functional groups on the modified carbon cloth, which facilitated the attachment of exoelectrogenic bacteria. Scanning electron microscopy (SEM) images showed a rougher surface on the modified carbon cloth, thereby increasing the area available for microbial colonization. MFC-2 achieved a higher maximum open-circuit voltage of 0.811 V, compared to 0.454 V for MFC-1. Polarization curves demonstrated peak power densities of 44.42 mW/m² for MFC-1 and 64.40 mW/m² for MFC-2. Electrochemical impedance spectroscopy (EIS) indicated a smaller Nyquist semicircle for MFC-2, suggesting reduced charge transfer resistance. SEM analysis of the biofilm on the anodes confirmed improved microbial adhesion on the modified carbon cloth. The research highlights the effectiveness of Fe₂O₃/H₂O₂-modified carbon cloth anodes in boosting the performance of microbial fuel cells (MFCs) for distillery wastewater treatment. This finding underscores the critical role of electrode surface modifications in enhancing microbial attachment and facilitating efficient electron transfer.

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4-Aminophenol (4-AP), widely used in pharmaceuticals, dyes, and photographic chemicals, poses serious environmental and health risks due to its toxicity and persistence. Conventional detection methods such as chromatography and spectrophotometry are reliable but costly, time-consuming, and require complex preparation. Electrochemical sensing provides a faster and more sensitive alternative. Nanocomposite-modified electrodes can further enhance sensitivity, with polyvinylidene fluoride (PVDF) offering excellent conductivity and cobalt ferrite (CoFe₂O₄) contributing redox activity and stability. CoFe₂O₄ nanoparticles with a cubic spinel structure were synthesized by a sol–gel method and blended with PVDF (1:10 w/w) to form a nanocomposite. This was drop-cast onto a pencil graphite electrode (PGE) to prepare PGE/PVDF-CoFe₂O₄. The material was characterized by XRD, FTIR, and FESEM, while electrochemical performance was assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The PGE/PVDF-CoFe₂O₄ electrode showed strong electrocatalytic activity for 4-AP reduction, achieving a linear detection range of 5–200 nM, a detection limit of 0.33 nM, and high sensitivity (23.03 μA·nM⁻¹·cm⁻²). Real wastewater analysis confirmed excellent recovery and reliability. The synergistic effects of PVDF conductivity and CoFe₂O₄ electrocatalysis enabled efficient electron transfer, establishing the nanocomposite as a promising transducer for environmental and pharmaceutical monitoring.

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